ext: move syscall wrappers from container

These are generally useful, and none of them are container-specific. Syscalls subtle to use and requiring container-specific setup remains in container.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/syscall.go

@@ -7,40 +7,9 @@ import (
 	"hakurei.app/ext"
 )
 
-// Prctl manipulates various aspects of the behavior of the calling thread or process.
-func Prctl(op, arg2, arg3 uintptr) error {
-	r, _, errno := Syscall(SYS_PRCTL, op, arg2, arg3)
-	if r < 0 {
-		return errno
-	}
-	return nil
-}
-
-// SetPtracer allows processes to ptrace(2) the calling process.
-func SetPtracer(pid uintptr) error { return Prctl(PR_SET_PTRACER, pid, 0) }
-
-// linux/sched/coredump.h
-const (
-	SUID_DUMP_DISABLE = iota
-	SUID_DUMP_USER
-)
-
-// SetDumpable sets the "dumpable" attribute of the calling process.
-func SetDumpable(dumpable uintptr) error { return Prctl(PR_SET_DUMPABLE, dumpable, 0) }
-
 // SetNoNewPrivs sets the calling thread's no_new_privs attribute.
-func SetNoNewPrivs() error { return Prctl(PR_SET_NO_NEW_PRIVS, 1, 0) }
-
-// Isatty tests whether a file descriptor refers to a terminal.
-func Isatty(fd int) bool {
-	var buf [8]byte
-	r, _, _ := Syscall(
-		SYS_IOCTL,
-		uintptr(fd),
-		TIOCGWINSZ,
-		uintptr(unsafe.Pointer(&buf[0])),
-	)
-	return r == 0
+func SetNoNewPrivs() error {
+	return ext.Prctl(PR_SET_NO_NEW_PRIVS, 1, 0)
 }
 
 // schedParam is equivalent to struct sched_param from include/linux/sched.h.
@@ -73,19 +42,3 @@ func schedSetscheduler(tid int, policy ext.SchedPolicy, param *schedParam) error
 	}
 	return nil
 }
-
-// IgnoringEINTR makes a function call and repeats it if it returns an
-// EINTR error. This appears to be required even though we install all
-// signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
-// Also #20400 and #36644 are issues in which a signal handler is
-// installed without setting SA_RESTART. None of these are the common case,
-// but there are enough of them that it seems that we can't avoid
-// an EINTR loop.
-func IgnoringEINTR(fn func() error) error {
-	for {
-		err := fn()
-		if err != EINTR {
-			return err
-		}
-	}
-}